As shown in FIG. 1, a biplane X-ray imaging apparatus (mainly developed for cardio vascular inspection) has two imaging systems to perform imaging from two directions simultaneously. One imaging system has a front imaging system 1 including an X-ray tube 3 and an X-ray detector 4 for obtaining an image of a patient on a plate of a bed from a front side. The other imaging system has a lateral imaging system 2 including an X-ray tube 5 and an X-ray detector 6 for imaging the patient from a lateral-side.
In the biplane X-ray imaging apparatus, the X-rays generated from the X-ray tube 3 of the front imaging system 1 pass through the patient P to directly enter the X-ray detector 4, and also reflect to enter the X-ray detector 6 as scattered X-rays. Similarly, the X-rays generated from the X-ray tube 5 of the front imaging system 2 pass through the patient P to enter the X-ray detector 6, and also reflect inside the patient P to enter the X-ray detector 4 as scattered X-rays.
Therefore, in an imaging sequence, as shown in FIG. 2 and FIGS. 3A-3D, when the X-rays are generated from the X-ray tube 3 of the front imaging system 1 and a signal is read out from the X-ray detector 4 of the front imaging system 1, a signal is read out from the X-ray detector 6 of the lateral imaging system 2 to remove an electric charge generated by the scattered X-rays. After the signal is read out, when the X-rays are generated by the X-ray tube 5 of the lateral imaging system 2 and a signal is read from the X-ray detector 6 of the lateral imaging system 2, a signal is read out from the X-ray detector 4 of the front imaging system 1 to remove an electric charge generated by the scattered X-rays.
Although the influence of each of the scattered X-rays between the front imaging system 1 and lateral imaging system 2 can be removed by the above-mentioned method, the imaging is performed by a double cycle of the minimum cycle of each X-ray detector. That is, an effective frame rate (the number of the frames per unit time) decreases to half of the maximum speed.
As a non-limiting example, it is conceptually desirable that a cardiac imaging is simultaneously performed from the front and lateral sides. However, since the imaging of the front imaging system 1 and the lateral imaging system 2 are performed in turn at a fixed cycle to avoid the influence of the scattered X-rays, the time gap between the front and lateral sides still remains.
In addition, a biplane X-ray diagnosis apparatus is described in Japanese Patent Publication (Kokai) No. 2000-102529.